GI.GLib.Structs.Date

GDate is a struct for calendrical calculations.

The GDate data structure represents a day between January 1, Year 1, and sometime a few thousand years in the future (right now it will go to the year 65535 or so, but dateSetParse only parses up to the year 8000 or so - just count on "a few thousand"). GDate is meant to represent everyday dates, not astronomical dates or historical dates or ISO timestamps or the like. It extrapolates the current Gregorian calendar forward and backward in time; there is no attempt to change the calendar to match time periods or locations. GDate does not store time information; it represents a day.

The GDate implementation has several nice features; it is only a 64-bit struct, so storing large numbers of dates is very efficient. It can keep both a Julian and day-month-year representation of the date, since some calculations are much easier with one representation or the other. A Julian representation is simply a count of days since some fixed day in the past; for Date the fixed day is January 1, 1 AD. ("Julian" dates in the Date API aren't really Julian dates in the technical sense; technically, Julian dates count from the start of the Julian period, Jan 1, 4713 BC).

GDate is simple to use. First you need a "blank" date; you can get a dynamically allocated date from dateNew, or you can declare an automatic variable or array and initialize it by calling dateClear. A cleared date is safe; it's safe to call dateSetDmy and the other mutator functions to initialize the value of a cleared date. However, a cleared date is initially invalid, meaning that it doesn't represent a day that exists. It is undefined to call any of the date calculation routines on an invalid date. If you obtain a date from a user or other unpredictable source, you should check its validity with the dateValid predicate. dateValid is also used to check for errors with dateSetParse and other functions that can fail. Dates can be invalidated by calling dateClear again.

It is very important to use the API to access the GDate struct. Often only the day-month-year or only the Julian representation is valid. Sometimes neither is valid. Use the API.

GLib also features GDateTime which represents a precise time.

Exported types

newtype Date

Memory-managed wrapper type.

Constructors

Date (ManagedPtr Date)

Instances

Eq Date

Defined in GI.GLib.Structs.Date

Methods

(==) :: Date -> Date -> Bool

(/=) :: Date -> Date -> Bool

GBoxed Date

Defined in GI.GLib.Structs.Date

ManagedPtrNewtype Date

Defined in GI.GLib.Structs.Date

Methods

toManagedPtr :: Date -> ManagedPtr Date

TypedObject Date

Defined in GI.GLib.Structs.Date

Methods

glibType :: IO GType

HasParentTypes Date

Defined in GI.GLib.Structs.Date

tag ~ 'AttrSet => Constructible Date tag

Defined in GI.GLib.Structs.Date

Methods

new :: MonadIO m => (ManagedPtr Date -> Date) -> [AttrOp Date tag] -> m Date

IsGValue (Maybe Date)

Convert Date to and from GValue. See toGValue and fromGValue.

Defined in GI.GLib.Structs.Date

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe Date -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe Date)

type ParentTypes Date

Defined in GI.GLib.Structs.Date

type ParentTypes Date = '[] :: [Type]

newZeroDate :: MonadIO m => m Date

Construct a Date struct initialized to zero.

Methods

Click to display all available methods, including inherited ones

Methods

addDays, addMonths, addYears, clamp, clear, compare, copy, daysBetween, free, isFirstOfMonth, isLastOfMonth, order, subtractDays, subtractMonths, subtractYears, toStructTm, valid.

Getters

getDay, getDayOfYear, getIso8601WeekOfYear, getJulian, getMondayWeekOfYear, getMonth, getSundayWeekOfYear, getWeekday, getYear.

Setters

setDay, setDmy, setJulian, setMonth, setParse, setTime, setTimeT, setTimeVal, setYear.

addDays

dateAddDays

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to increment

-> Word32

nDays: number of days to move the date forward

-> m ()

Increments a date some number of days. To move forward by weeks, add weeks*7 days. The date must be valid.

addMonths

dateAddMonths

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to increment

-> Word32

nMonths: number of months to move forward

-> m ()

Increments a date by some number of months. If the day of the month is greater than 28, this routine may change the day of the month (because the destination month may not have the current day in it). The date must be valid.

addYears

dateAddYears

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to increment

-> Word32

nYears: number of years to move forward

-> m ()

Increments a date by some number of years. If the date is February 29, and the destination year is not a leap year, the date will be changed to February 28. The date must be valid.

clamp

dateClamp

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to clamp

-> Date

minDate: minimum accepted value for date

-> Date

maxDate: maximum accepted value for date

-> m ()

If date is prior to minDate, sets date equal to minDate. If date falls after maxDate, sets date equal to maxDate. Otherwise, date is unchanged. Either of minDate and maxDate may be Nothing. All non-Nothing dates must be valid.

clear

dateClear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: pointer to one or more dates to clear

-> Word32

nDates: number of dates to clear

-> m ()

Initializes one or more Date structs to a safe but invalid state. The cleared dates will not represent an existing date, but will not contain garbage. Useful to init a date declared on the stack. Validity can be tested with dateValid.

compare

dateCompare

Arguments

:: (HasCallStack, MonadIO m)

=> Date

lhs: first date to compare

-> Date

rhs: second date to compare

-> m Int32

Returns: 0 for equal, less than zero if lhs is less than rhs, greater than zero if lhs is greater than rhs

qsort()-style comparison function for dates. Both dates must be valid.

copy

dateCopy

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to copy

-> m Date

Returns: a newly-allocated Date initialized from date

Copies a GDate to a newly-allocated GDate. If the input was invalid (as determined by dateValid), the invalid state will be copied as is into the new object.

Since: 2.56

daysBetween

dateDaysBetween

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date1: the first date

-> Date

date2: the second date

-> m Int32

Returns: the number of days between date1 and date2

Computes the number of days between two dates. If date2 is prior to date1, the returned value is negative. Both dates must be valid.

free

dateFree

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to free

-> m ()

Frees a Date returned from dateNew.

getDay

dateGetDay

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to extract the day of the month from

-> m Word8

Returns: day of the month

Returns the day of the month. The date must be valid.

getDayOfYear

dateGetDayOfYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to extract day of year from

-> m Word32

Returns: day of the year

Returns the day of the year, where Jan 1 is the first day of the year. The date must be valid.

getDaysInMonth

dateGetDaysInMonth

Arguments

:: (HasCallStack, MonadIO m)

=> DateMonth

month: month

-> Word16

year: year

-> m Word8

Returns: number of days in month during the year

Returns the number of days in a month, taking leap years into account.

getIso8601WeekOfYear

dateGetIso8601WeekOfYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a valid Date

-> m Word32

Returns: ISO 8601 week number of the year.

Returns the week of the year, where weeks are interpreted according to ISO 8601.

Since: 2.6

getJulian

dateGetJulian

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to extract the Julian day from

-> m Word32

Returns: Julian day

Returns the Julian day or "serial number" of the Date. The Julian day is simply the number of days since January 1, Year 1; i.e., January 1, Year 1 is Julian day 1; January 2, Year 1 is Julian day 2, etc. The date must be valid.

getMondayWeekOfYear

dateGetMondayWeekOfYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> m Word32

Returns: week of the year

Returns the week of the year, where weeks are understood to start on Monday. If the date is before the first Monday of the year, return 0. The date must be valid.

getMondayWeeksInYear

dateGetMondayWeeksInYear

Arguments

:: (HasCallStack, MonadIO m)

=> Word16

year: a year

-> m Word8

Returns: number of Mondays in the year

Returns the number of weeks in the year, where weeks are taken to start on Monday. Will be 52 or 53. The date must be valid. (Years always have 52 7-day periods, plus 1 or 2 extra days depending on whether it's a leap year. This function is basically telling you how many Mondays are in the year, i.e. there are 53 Mondays if one of the extra days happens to be a Monday.)

getMonth

dateGetMonth

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to get the month from

-> m DateMonth

Returns: month of the year as a DateMonth

Returns the month of the year. The date must be valid.

getSundayWeekOfYear

dateGetSundayWeekOfYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> m Word32

Returns: week number

Returns the week of the year during which this date falls, if weeks are understood to begin on Sunday. The date must be valid. Can return 0 if the day is before the first Sunday of the year.

getSundayWeeksInYear

dateGetSundayWeeksInYear

Arguments

:: (HasCallStack, MonadIO m)

=> Word16

year: year to count weeks in

-> m Word8

Returns: the number of weeks in year

Returns the number of weeks in the year, where weeks are taken to start on Sunday. Will be 52 or 53. The date must be valid. (Years always have 52 7-day periods, plus 1 or 2 extra days depending on whether it's a leap year. This function is basically telling you how many Sundays are in the year, i.e. there are 53 Sundays if one of the extra days happens to be a Sunday.)

getWeekday

dateGetWeekday

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> m DateWeekday

Returns: day of the week as a DateWeekday.

Returns the day of the week for a Date. The date must be valid.

getYear

dateGetYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> m Word16

Returns: year in which the date falls

Returns the year of a Date. The date must be valid.

isFirstOfMonth

dateIsFirstOfMonth

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to check

-> m Bool

Returns: True if the date is the first of the month

Returns True if the date is on the first of a month. The date must be valid.

isLastOfMonth

dateIsLastOfMonth

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to check

-> m Bool

Returns: True if the date is the last day of the month

Returns True if the date is the last day of the month. The date must be valid.

isLeapYear

dateIsLeapYear

Arguments

:: (HasCallStack, MonadIO m)

=> Word16

year: year to check

-> m Bool

Returns: True if the year is a leap year

Returns True if the year is a leap year.

For the purposes of this function, leap year is every year divisible by 4 unless that year is divisible by 100. If it is divisible by 100 it would be a leap year only if that year is also divisible by 400.

new

dateNew

Arguments

:: (HasCallStack, MonadIO m)

=> m Date

Returns: a newly-allocated Date

Allocates a Date and initializes it to a safe state. The new date will be cleared (as if you'd called dateClear) but invalid (it won't represent an existing day). Free the return value with dateFree.

newDmy

dateNewDmy

Arguments

:: (HasCallStack, MonadIO m)

=> Word8

day: day of the month

-> DateMonth

month: month of the year

-> Word16

year: year

-> m Date

Returns: a newly-allocated Date initialized with day, month, and year

Create a new Date representing the given day-month-year triplet.

The triplet you pass in must represent a valid date. Use dateValidDmy if needed to validate it. The returned Date is guaranteed to be non-Nothing and valid.

newJulian

dateNewJulian

Arguments

:: (HasCallStack, MonadIO m)

=> Word32

julianDay: days since January 1, Year 1

-> m Date

Returns: a newly-allocated Date initialized with julianDay

Create a new Date representing the given Julian date.

The julianDay you pass in must be valid. Use dateValidJulian if needed to validate it. The returned Date is guaranteed to be non-Nothing and valid.

order

dateOrder

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date1: the first date

-> Date

date2: the second date

-> m ()

Checks if date1 is less than or equal to date2, and swap the values if this is not the case.

setDay

dateSetDay

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> Word8

day: day to set

-> m ()

Sets the day of the month for a Date. If the resulting day-month-year triplet is invalid, the date will be invalid.

setDmy

dateSetDmy

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> Word8

day: day

-> DateMonth

month: month

-> Word16

y: year

-> m ()

Sets the value of a Date from a day, month, and year. The day-month-year triplet must be valid; if you aren't sure it is, call dateValidDmy to check before you set it.

setJulian

dateSetJulian

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> Word32

julianDate: Julian day number (days since January 1, Year 1)

-> m ()

Sets the value of a Date from a Julian day number.

setMonth

dateSetMonth

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> DateMonth

month: month to set

-> m ()

Sets the month of the year for a Date. If the resulting day-month-year triplet is invalid, the date will be invalid.

setParse

dateSetParse

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to fill in

-> Text

str: string to parse

-> m ()

Parses a user-inputted string str, and try to figure out what date it represents, taking the [current locale][setlocale] into account. If the string is successfully parsed, the date will be valid after the call. Otherwise, it will be invalid. You should check using dateValid to see whether the parsing succeeded.

This function is not appropriate for file formats and the like; it isn't very precise, and its exact behavior varies with the locale. It's intended to be a heuristic routine that guesses what the user means by a given string (and it does work pretty well in that capacity).

setTime

dateSetTime

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date.

-> Int32

time_: GTime value to set.

-> m ()

Deprecated: (Since version 2.10)Use dateSetTimeT instead.

Sets the value of a date from a GTime value. The time to date conversion is done using the user's current timezone.

setTimeT

dateSetTimeT

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> CTime

timet: time_t value to set

-> m ()

Sets the value of a date to the date corresponding to a time specified as a time_t. The time to date conversion is done using the user's current timezone.

To set the value of a date to the current day, you could write:

C code

time_t now = time (NULL);
if (now == (time_t) -1)
  // handle the error
g_date_set_time_t (date, now);

Since: 2.10

setTimeVal

dateSetTimeVal

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> TimeVal

timeval: TimeVal value to set

-> m ()

Deprecated: (Since version 2.62)tTimeVal is not year-2038-safe. Use dateSetTimeT instead.

Sets the value of a date from a TimeVal value. Note that the tvUsec member is ignored, because Date can't make use of the additional precision.

The time to date conversion is done using the user's current timezone.

Since: 2.10

setYear

dateSetYear

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date

-> Word16

year: year to set

-> m ()

Sets the year for a Date. If the resulting day-month-year triplet is invalid, the date will be invalid.

strftime

dateStrftime

Arguments

:: (HasCallStack, MonadIO m)

=> Text

s: destination buffer

-> CSize

slen: buffer size

-> Text

format: format string

-> Date

date: valid Date

-> m CSize

Returns: number of characters written to the buffer, or 0 the buffer was too small

Generates a printed representation of the date, in a [locale][setlocale]-specific way. Works just like the platform's C library strftime() function, but only accepts date-related formats; time-related formats give undefined results. Date must be valid. Unlike strftime() (which uses the locale encoding), works on a UTF-8 format string and stores a UTF-8 result.

This function does not provide any conversion specifiers in addition to those implemented by the platform's C library. For example, don't expect that using dateStrftime would make the %F provided by the C99 strftime() work on Windows where the C library only complies to C89.

subtractDays

dateSubtractDays

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to decrement

-> Word32

nDays: number of days to move

-> m ()

Moves a date some number of days into the past. To move by weeks, just move by weeks*7 days. The date must be valid.

subtractMonths

dateSubtractMonths

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to decrement

-> Word32

nMonths: number of months to move

-> m ()

Moves a date some number of months into the past. If the current day of the month doesn't exist in the destination month, the day of the month may change. The date must be valid.

subtractYears

dateSubtractYears

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to decrement

-> Word32

nYears: number of years to move

-> m ()

Moves a date some number of years into the past. If the current day doesn't exist in the destination year (i.e. it's February 29 and you move to a non-leap-year) then the day is changed to February 29. The date must be valid.

toStructTm

dateToStructTm

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to set the struct tm from

-> Ptr ()

tm: struct tm to fill

-> m ()

Fills in the date-related bits of a struct tm using the date value. Initializes the non-date parts with something safe but meaningless.

valid

dateValid

Arguments

:: (HasCallStack, MonadIO m)

=> Date

date: a Date to check

-> m Bool

Returns: Whether the date is valid

Returns True if the Date represents an existing day. The date must not contain garbage; it should have been initialized with dateClear if it wasn't allocated by one of the dateNew variants.

validDay

dateValidDay

Arguments

:: (HasCallStack, MonadIO m)

=> Word8

day: day to check

-> m Bool

Returns: True if the day is valid

Returns True if the day of the month is valid (a day is valid if it's between 1 and 31 inclusive).

validDmy

dateValidDmy

Arguments

:: (HasCallStack, MonadIO m)

=> Word8

day: day

-> DateMonth

month: month

-> Word16

year: year

-> m Bool

Returns: True if the date is a valid one

Returns True if the day-month-year triplet forms a valid, existing day in the range of days Date understands (Year 1 or later, no more than a few thousand years in the future).

validJulian

dateValidJulian

Arguments

:: (HasCallStack, MonadIO m)

=> Word32

julianDate: Julian day to check

-> m Bool

Returns: True if the Julian day is valid

Returns True if the Julian day is valid. Anything greater than zero is basically a valid Julian, though there is a 32-bit limit.

validMonth

dateValidMonth

Arguments

:: (HasCallStack, MonadIO m)

=> DateMonth

month: month

-> m Bool

Returns: True if the month is valid

Returns True if the month value is valid. The 12 DateMonth enumeration values are the only valid months.

validWeekday

dateValidWeekday

Arguments

:: (HasCallStack, MonadIO m)

=> DateWeekday

weekday: weekday

-> m Bool

Returns: True if the weekday is valid

Returns True if the weekday is valid. The seven DateWeekday enumeration values are the only valid weekdays.

validYear

dateValidYear

Arguments

:: (HasCallStack, MonadIO m)

=> Word16

year: year

-> m Bool

Returns: True if the year is valid

Returns True if the year is valid. Any year greater than 0 is valid, though there is a 16-bit limit to what Date will understand.

Properties

day

the day of the day-month-year representation of the date, as a number between 1 and 31

getDateDay :: MonadIO m => Date -> m Word32

Get the value of the “day” field. When overloading is enabled, this is equivalent to

get date #day

setDateDay :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “day” field. When overloading is enabled, this is equivalent to

set date [ #day := value ]

dmy

this is set if day, month and year are valid

getDateDmy :: MonadIO m => Date -> m Word32

Get the value of the “dmy” field. When overloading is enabled, this is equivalent to

get date #dmy

setDateDmy :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “dmy” field. When overloading is enabled, this is equivalent to

set date [ #dmy := value ]

julian

this bit is set if julianDays is valid

getDateJulian :: MonadIO m => Date -> m Word32

Get the value of the “julian” field. When overloading is enabled, this is equivalent to

get date #julian

setDateJulian :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “julian” field. When overloading is enabled, this is equivalent to

set date [ #julian := value ]

julianDays

the Julian representation of the date

getDateJulianDays :: MonadIO m => Date -> m Word32

Get the value of the “julian_days” field. When overloading is enabled, this is equivalent to

get date #julianDays

setDateJulianDays :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “julian_days” field. When overloading is enabled, this is equivalent to

set date [ #julianDays := value ]

month

the month of the day-month-year representation of the date, as a number between 1 and 12

getDateMonth :: MonadIO m => Date -> m Word32

Get the value of the “month” field. When overloading is enabled, this is equivalent to

get date #month

setDateMonth :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “month” field. When overloading is enabled, this is equivalent to

set date [ #month := value ]

year

the year of the day-month-year representation of the date

getDateYear :: MonadIO m => Date -> m Word32

Get the value of the “year” field. When overloading is enabled, this is equivalent to

get date #year

setDateYear :: MonadIO m => Date -> Word32 -> m ()

Set the value of the “year” field. When overloading is enabled, this is equivalent to

set date [ #year := value ]